Beijing announced on Wednesday its GDP grew by 5.4% between January and March, compared with the same period a year earlier.
The figure has exceeded expectations but reflects the period before US tariffs jumped from 10% to 145%, and Chinese officials warned of more economic pain ahead.
While both Washington and Beijing have said they are open to negotiating, neither have made a move to do so yet.
When that happens, Li, 58, will play a key role. He previously served as a deputy permanent representative to the United Nations in Geneva and has held several key jobs in the commerce ministry.
Speaking to Reuters, one expert said the change in jobs was "very abrupt and potentially disruptive" given the current trade tensions - adding that Wang also had experience negotiating with US since the first Trump administration.
"It might be that in the view of China's top leadership, given how tensions have continued escalating, they need someone else to break the impasse... and finally start negotiating," said Alfredo Montufar-Helu, a senior adviser to the Conference Board's China Centre.
However, another analyst who spoke to Reuters suggested the move could just be a "routine promotion" that just happened to come at a particularly tense period in time.